For many musicians, there's no question about it: tubes are the best way to go. If you're here looking for tubes, you're probably in the same boat. Fortunately, there are plenty of tubes available for your instrument amps, from vintage models dating back to the tube's golden era all the way to modern amps that stick to tube-based circuitry for that irreplaceable character they can add to your sound. Generally, the most crucial tubes in your amplifier are the preamp tubes. Responsible for handling the raw signal from your instrument and pedals, the preamp section not only gives a power boost, it also defines the overall tone and gain of the sound. Because the preamp tubes are so central to the amp's function, changing them has a big impact. If you want to learn about all the different sounds your amp is capable of, experimenting with various preamp tubes is a great place to start. In an amplifier with more than one preamp tube, pay special attention to the very first one, nearest to the input—it's in the point position, and that means it's going to have the greatest effect of any one tube on the sound that eventually comes out of the amp. Power tubes come later in the amplifier's circuitry, and their job is to kick up the power level of the signal so that it can drive those big speakers. With this role to fill, power tubes don't quite have the same impact on your sound as preamp tubes—but that isn't to say they have none. If your preamp tubes were coffee, the power tubes would be cream and sugar: they don't create the 'flavor', but they sweeten it to taste. Depending on your amplifier, you may also have rectifier tubes to customize. Many tube amps use solid-state rectifiers, so you're most likely to need one of these tubes if you're using a vintage amp or a strictly all-tube model. Rectifier tubes can be difficult to classify because they don't have a direct impact on your sound. The rectifier determines the voltage that goes to the other tubes, and those tubes will give a slightly different sound at different voltages. But rectifier tubes do have one quirk that plays into your sound: when you come in strong on the attack, the tube will drop the voltage, giving a distinctively soft lead-in that builds to a swelling note as the voltage goes back to normal. When you're choosing your rectifier tubes, it's this characteristic that you're looking for. If you have a hybrid amplifier, you may only have preamp tubes—or maybe you have an antique amp that needs all three. It all comes down to what you need, whether you're fine-tuning your sound or just stocking up on replacements of your favorite tube.